Updated September 12, 2014.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
What is Idiopathic Intracranial Hypertension?
Idiopathic Intracranial Hypertension (IIH) is a medical condition that results from increased spinal fluid pressure around the brain, in the absence of a tumor or other brain disorder. It is formerly known as pseudotumor cerebri. It is most common in women who are obese and in their childbearing years.
Headache and vision changes are the classic symptoms seen in IIH.
On an eye examination, doctors will see papilledema. Papilledema is a condition characterized by optic disc swelling of the eye, due to increased pressure in the brain. It is diagnosed by a doctor during an ophthalmoscopic examination.
Other common (but not exclusive) symptoms seen in patients with IIH include:
- transient visual changes
- pulsatile tinnitus (hearing a pulsating or throbbing noise in your head)
- photopsia (perceiving flashes of light)
- pain behind the eyes
- double vision
- vision loss
What is the Headache of IIH like?
A headache from IIH can mimic that of a migraine or tension-type headache, making the diagnosis tricky. Plus, there is not one specific "type of headache" that people with IIH have. Classically, the headache associated with IIH is severe and throbbing, but this is not always the case. The pain can be intermittent or constant and may be associated with nausea and/or vomiting. Sometimes, people with an IIH headache will note pain behind their eyes and/or pain with eye movement.
How is IIH Diagnosed?
If a doctor suspects IIH and sees papilledema on a eye exam, then he will order an MRI of the brain with and without contrast to check for an underlying cause of your increased intracranial pressure. Secondary causes of intracranial hypertension include (but not limited to):
- Cerebral venous thrombosis
- Brain tumor or abscess (collection of infected fluid)
- Obstructive hydrocephalus
- Subarachnoid Hemorrhage
- Malignant Hypertension
If there is no cause seen on the MRI, then you will undergo a lumbar puncture to confirm the elevated pressure and to rule out infection through analysis of the cerebrospinal fluid or CSF. In IIH, there is no infection, so the composition of the CSF is normal. But, the lumbar puncture will show an opening pressure greater than 250 mmH2O, which is diagnostic for an elevated intracranial pressure.
Treatment of IIH
Treatment of IIH requires close followup with a neurologist and opthamalogist. The mainstay therapy for IIH is acetazolamide, a carbonic anhydrase inhibitor, which reduces the rate of CSF production. Your doctor may consider other therapies if you have a sulfa allergy or are pregnant, as these are relative contraindications to taking acetazolamide. Sometimes, serial lumbar punctures and corticosteroids, which help lower the CSF pressure, may be used in the short-term, but these are not long-term solutions.
If an individual's headache is resistant to medical therapy and/or she is suffering from progressive vision loss, surgery is needed. Surgical intervention entails procedures called optic nerve sheath fenestration (ONSF) and/or a CSF shunting procedure. In optic nerve sheath fenestration, a slit or window is made in the optic nerve sheath. This allows CSF to drain, alleviating pressure on the nerve, permitting vision to be partially or fully restored. In CSF shunting, spinal fluid is diverted to other parts of the body, again alleviating pressure on the brain.
Take Home Message
The headache of IIH is variable and is produced by increased intracranial pressure, signified by papilledema on an eye examination. Treatment is critical and urgent to prevent vision loss and requires close-followup with your neurologist and opthamalogist.
Lee AG & Wall M. Idiopathic intracranial hypertension: Clinical features and diagnosis. In: UpToDate, Basow DS (ed), UpToDate, Waltham, MA, 2014.
Lee AG & Wall M. Idiopathic intracranial hypertension (pseudotumor cerebri): Prognosis and treatment. In: UpToDate, Basow DS (ed), UpToDate, Waltham, MA, 2014.
NINDS Pseudotumor Cerebri Information Page. http://www.ninds.nih.gov/disorders/pseudotumorcerebri/pseudotumorcerebri.htm. Accessed Sept 2014.
Pineles SL, Volpe NJ. Long-Term Results of Optic Nerve Sheath Fenestration for Idiopathic Intracranial Hypertension: Earlier Intervention Favours Improved Outcomes. Neuro-Ophthalmology. 2013;37(1):12-19.
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